Cranium

This is not quite completed but shows it almost done. I'm in process of testing animations and timing. Items to complete are:

add the pressure sensors

mount the RGB LEDs in blocks

put the PCBs in a box

patch the big hole I cut in the closet

I am illuminating the stairs using 30 RGB leds. Control of the LEDs is done using an ATmega328 processor (Arduino) and 6 TLC5940 LED driver ICs. Pressure sensors will be used to detect someone going on the staircase which also allows me to calibrate it so my dog won't trigger it. A light detector will be used to only trigger it at night.

I am adding themes to the animations so at the end of the video, you will see the Xmas theme. A halloween theme will be added that will have red pulsating lights. Other holidays, I haven't quite thought of yet.

This is the first project on the Arduino I started on a couple of months ago and while waiting for parts, I built some LED cubes. It took a long time to plan, breadboard a prototype and then install. There are 120 wires that had to be run under the staircase to the closet underneath. This project is not for the faint of heart! LOL.

Peak amperage is about 1.4A @ 5V being regulated down from a 7.5V 2.5A wall wart power supply.

Cranium

Finished up the stairs this weekend. Pressure senors installed and calibrated. LEDs mounted. Light sensor installed and calibrated. All that is left is to tidy up the mess in the closet under the stairs.

Cranium

Why is there blue in the Christmas theme?I thought christmas was all about the red and green

Those are the main colors you see in non-lit items for x-mas. But for lights, it's all about multi-colors. http://www.google.com/search?q=xmas+lights&hl=en&client=opera&hs=bG2&rls=en&channel=suggest&prmd=imvns&source=lnms&tbm=isch&ei=FHylTpzALYWhtwfN7YSSCA&sa=X&oi=mode_link&ct=mode&cd=2&ved=0CGcQ_AUoAQ&biw=1342&bih=794

Cranium

A few details on the project.....((click on the images for a larger version)

This is the opening I cut below the staircase to route the wires.....still need to patch it. I used 28ga and 30ga ribbon cable for the wiring...I cannot see any difference in brightness levels between them.

This shows the stacked boards with ATMega328 board on top. Basic setup with pin headers to allow reprogramming without removing the IC. Yes, that is a rubber band holding several heat sinks on the voltage regulator. That will be removed once it is in a box with a small fan. Currently, it barely gets warm with normal use but when I'm running it constantly for testing or demonstration, it does get a bit warm.

Side view of the boards that shows the pin headers and 6 TLC5940 LED driver ICs.

Cranium

Yes. The 3 boards below the processor board are addressing each of the colors and each has 30 pins for each LED (2 on each step). I could have used multiplexing to reduce the number of TLC5940s, but the wiring would have been the same so I decided to ensure maximum brightness by driving each separately.

The processor board also provides the +5V pin headers for each of the LEDs.

Cranium

I'm assuming that the led pins are all in a paralell circuit, right? Otherwise what are you using to power the whole thing?

Not sure as to exactly what is meant by having all led pins in a parallel circuit but the circuit design uses 6 TLC5940s that are in series. The data out for the first drives the data in for the next and that data out drives the data in for the next and so on...

The first two TLC5940s drive the red, the second two drive the green and the last two drive the blue.

I used this library for the control of the TLC5940s: http://code.google.com/p/tlc5940arduino/

Peak amperage that I saw was about 1.4A at 5V and I am using a 7.5V, 2.5A wall wart as a power supply.

Cranium

Well i mean a series circuit is, for example, having leds one after another on one line of power. Where as a paralell would be more having 1 led part off into its own line and then reconnect.

Are you using any capacitors on your project?

Gotcha.....the control circuit is series but the LEDs would be parallel. Each is individually powered and sunk to its own pin on the TLC5940. Yes, I am using capacitors. A 100nf and 10uf capacitor worked fine in breadboard but then when I powered the breadboard from my wall wart and 5v regulator, it had issues so replaced a couple 100nf with 1000nf and no more issues. It would have likely worked with just the 100nf once everything was on PCB because another noise issue on the breadboard causing intermittent flickering went away as well.

The VR I'm using is rated at 1.5A so I am pretty much peaking it out. When I used a 12V power source, it got over 300°F and went into thermal shutdown which is why I started using the 7.5V power source. If I run all the lights at maximum brightness (RGB on each LED) for an extended period of time, it will still get pretty hot but won't go into thermal shutdown. But since I'm not ever running at full power but for brief transitions, and most of the time it is well below 1A, it only gets slightly warm. I'm still putting small fan in the box it will reside in just to be on the safe side though.